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Biotypes of BVD (Type does not affect immune response!) Cytopathic Cytopathic Kills cells in tissue culture Kills cells in tissue culture Arises from a virus mutation Arises from a virus mutation Most common strain in vaccines Most common strain in vaccines Noncytopathic Does not change culture cells Most common biotype found in nature

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Genotypes of BVD Type 1 Type 1 Original strains of BVD that were isolated Original strains of BVD that were isolated Is included in all BVD vaccines Is included in all BVD vaccines *There is some cross protection with vaccines between types 1 & 2 *There is some cross protection with vaccines between types 1 & 2 Type 2 This type was more recently discovered Hemorrhagic syndrome strains Is included in most BVD vaccines now

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What is Persistent Infection? A PI calf is born infected with the virus A PI calf is born infected with the virus This can happen if the dam is a PI animal This can happen if the dam is a PI animal This can happen if the dam is transiently infected during pregnancy from another animal This can happen if the dam is transiently infected during pregnancy from another animal *The virus must be non-cytopathic* *The virus must be non-cytopathic* The calf must be infected between 40-100 days approximately The calf must be infected between 40-100 days approximately During this time the calf has no immune system so it recognizes the virus as “self” and never clears it During this time the calf has no immune system so it recognizes the virus as “self” and never clears it After this time, the calf’s immune system is developed enough to fight the virus After this time, the calf’s immune system is developed enough to fight the virus

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Manifestations of Calves infected in utero PI calf (Body does not recognize virus) PI calf (Body does not recognize virus) Virus is always circulating in body Virus is always circulating in body May die soon after birth May die soon after birth Many are clinically normal Many are clinically normal This is the natural reservoir of the virus This is the natural reservoir of the virus Infected in utero but not PI (infected around or after day 100) Congential defects Skeletal problems Dome shaped head Shortened lower jaw Eye abnormalities Brain defects Abortions Clinically normal calves Calves that are not killed can clear the virus and go on

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PI Calves PI calves are more likely to die than non- PI calves in the first year PI calves are more likely to die than non- PI calves in the first year Pneumonia Pneumonia Diarrhea Diarrhea Poor doer Poor doer Many look and perform like a healthy calf Many look and perform like a healthy calf

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Mucosal Disease This is Highly fatal syndrome in which the mucous membranes become ulcerated This is Highly fatal syndrome in which the mucous membranes become ulcerated Mouth Mouth Stomach Stomach Intestine Intestine Teats Teats Coronary bands of hooves Coronary bands of hooves

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Mucosal Dz, cont For mucosal disease to occur a PI calf (noncytopathic) must be superinfected with a cytopathic strain. For mucosal disease to occur a PI calf (noncytopathic) must be superinfected with a cytopathic strain. The more closely related the viruses are genetically, the worse the disease The more closely related the viruses are genetically, the worse the disease When a noncytopathic virus found in nature mutates to cytopathic & the calf is exposed When a noncytopathic virus found in nature mutates to cytopathic & the calf is exposed When the PI calf’s own noncytopathic strain mutates When the PI calf’s own noncytopathic strain mutates

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PI Calf Shedding PI calves shed the virus their entire life PI calves shed the virus their entire life Some periods they may shed a lot, and others not as much Some periods they may shed a lot, and others not as much Virus shed in saliva, tears, urine, feces, blood Virus shed in saliva, tears, urine, feces, blood There is so much virus shed, that most vaccines cannot protect other cattle against a PI There is so much virus shed, that most vaccines cannot protect other cattle against a PI Continue to infect cow herds and create more PI’s Continue to infect cow herds and create more PI’s

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PI Diagnosis Ear Notch Elisa Ear Notch Elisa Ear Notch Immunohistochemisty Ear Notch Immunohistochemisty Polymerase Chain Reaction Polymerase Chain Reaction Virus Isolation Virus Isolation These tests can be done at anytime in a PI’s life and only need to be done once. If positive, will always be positive. If negative, can be infected with BVD but will not be a PI If transiently infected, some tests may be positive, but the calf may need to be tested again in a month to confirm PI status

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BVD Control & Prevention Vaccination with a vaccine using Type 1 and Type 2 strains Vaccination with a vaccine using Type 1 and Type 2 strains Modified live vaccine creates a stronger, more natural immunity, is cheaper, and less doses required Modified live vaccine creates a stronger, more natural immunity, is cheaper, and less doses required Newer vaccines have label claims that if given to cow pre-breeding can successfully prevent PI in fetus Newer vaccines have label claims that if given to cow pre-breeding can successfully prevent PI in fetus

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BVD Control & Prevention, cont. Test herds for PI calves and remove all animals to quarantine** Test herds for PI calves and remove all animals to quarantine** Test all dams of PI calves to see if they are also PI Test all dams of PI calves to see if they are also PI Test all purchased breeding animals before entry into herd Test all purchased breeding animals before entry into herd

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